Large planes, commercial aircraft, jet aircraft and military helicopters are all equipped with very extensive heating, defogging and air conditioning systems for the cabin, whether in flight or on the ground.
Small aircraft, however, are normally equipped with simple systems which, when in flight, take in ambient air and the ram speed of the aircraft pushes the ambient air past an exhaust manifold or other source of heat and through ducts into the cabin. Unfortunately, when an aircraft is not in flight, there is no ram air pushing through the heating system. This creates serious problems in cold, wintry conditions, particularly in northern climates such as Canada or the northern United States. During start up, warm up, taxi, takeoff and prior to flight, the cabin is extremely cold and uncomfortable. A more serious problem, however, is that the pilot's visibility is poor because off fogging windows. During taxi and takeoff, this can lead to serious accidents. Therefore, it appears that some sort of auxiliary system during winter conditions for start up, taxi and takeoff is needed.
A review of the literature, prior art, and aircraft now in service, has revealed to the present inventor that this cold weather problem has not been solved, and pilots and passengers in small planes continue to complain.
Blowers have been used in heating and cooling application for some aircraft but none address the current problem. In U.S. Pat. No. 4,490,989, issued to Keen on Jan. 1, 1985, a helicopter heating and air conditioning system is described for turbine engine-powered helicopters. The invention is not directed to temporary heating during start up, taxi and takeoff but rather to a permanent system used in conjunction with an air conditioning system. A blower is used, however, it is located downstream of a condenser and is only effective for helicopter turbines. Use of this system with small planes would not be possible.
In U.S. Pat. No. 2,265,168, issued to W. E. Huffinan on Dec. 9, 1941, a heat exchanger is located within the exhaust manifold or exhaust pipes, the principal idea being that the pressure produced by a blower from the cold air inlet maintains pressure through the heat exchanger greater than the pressure within the exhaust manifold. Thus the blower is not used to push air past the exhaust manifold in the takeoff or taxiing position but rather is used to continuously keep the pressure up such that if a leak in the heat exchanger develops, CO or other exhaust gases will not enter into the system which provides warmed air to the cabin. The invention does not use a typical shrouded engine muff heat exchanger which is common in present day small planes but rather the heat exchanger is found within the exhaust manifold. Furthermore, this invention is not used on a temporary basis for start up, warm up, taxi and takeoff.